The present invention is in the field of an earth freezing apparatus and is more particularly directed to a unique heat pipe assembly and sub-components thereof for enhancing the freezing and maintenance of frozen soil for providing stabilized support of structures supported on or embedded in the soil.
It is has long been recognized that metal pipes having proper refrigerant on their interior can be embedded in the soil in areas having colder climates with their upper ends exposed to the atmosphere so that heat flows from the soil into the refrigerant which, when the air temperature is sufficiently low, is chilled by the cooler atmosphere and flows to the bottom of the pipe where it absorbs heat from the soil to complete the cycle. The heat absorbed from the soil results in maintaining the surrounding soil in frozen condition or promoting the growth of frozen soil. Pipes of the foregoing type are referred to as "heat pipes" and are disclosed in U.S. Pat. Nos. 3,217,791; 3,840,068; 3,935,900 and 4,090,555. The devices disclosed in patents of the aforementioned type comprise heat pipes having longitudinally extending generally radial fins at the upper exposed ends of the pipe for enhancing the flow of heat from the vapor on the interior of the pipe outwardly to the surrounding ambient atmosphere. The rate in which the heat flow occurs varies in accordance with a number of parameters including the temperature differential between the inside of the pipe and the ambient atmosphere of the refrigerant or working fluid used in the heat pipes and the wind velocity over the surface of the exposed pipe and associated fin arrangement. While increased wind velocity results in increased heat flow, the influence of the wind on the exposed pipe and fin arrangement fluctuates so much due to the climatological, geographic and weather variations as to render the forecasting of the amount of heat extraction for a particular installation extremely difficult. Consequently, heat pipes are frequently designed with a far greater capacity than is actually necessary in order to provide adequate heat extraction capacity for low wind velocity conditions. It has consequently been impossible to obtain optimum cost effectiveness in the design of heat pipe installations.